The present invention relates generally to composite containers with end caps and removable membranes and methods of sealing such containers.
Conventional containers for snack foods and other products often have a membrane sealed to a top rim of the container and a post-applied overcap or end cap covering the membrane, and a metal closure seamed onto a bottom rim of the container. Typically, the container manufacturer will seal the membrane to the top rim, apply the end cap to the container, and ship the container to a food packager. The food packager fills the container with the products through the open bottom of the container and then seams the metal closure to the bottom rim of the container. The container may be flushed or evacuated during the bottom seaming process in order to preserve the stored products for a longer period of time.
The sealed membrane provides a hermetic seal for protecting the products. The sealed membrane is removed by the customer when the container is first opened, and the membrane is discarded. The end cap is provided for re-closing the container after the initial opening. Typically, the end cap engages the rim (e.g., a rolled bead or a flange) on the top of the container in such a way that a snap-fit or interference fit connection exists to hold the end cap onto the container.
The metal closure seamed to the bottom rim also provides a hermetic seal for protecting the products. However, unlike the membrane sealed to the top rim, the bottom metal closure is not intended to be removable. Therefore the bottom seal is generally stronger than the top seal. Moreover, the bottom end of the container, including the bottom closure and the bottom seal, must be durable enough to withstand the rigors of shipping and handling.
Although a metal closure provides adequate protection, metal is an expensive material to use in a disposable container. Therefore there remains a need to provide a low-cost bottom closure for a container that can adequately protect the container and its contents during shipping and handling.